The present invention relates to an image shake correction device, and more particularly, to an image shake correction device that operates in a lens shift manner.
Image shake correction devices correct image shake when conducting photographing operations using photographing apparatus, such as still cameras and video cameras. Recently, as the number of pixels of imaging devices, such as a charge coupled device (CCD), has increased, when an image is enlarged and displayed on a display device, fine shaking can be observed. Thus, image shake correction devices are installed in small-sized digital cameras.
Image shake correction devices are classified into two types, image shake correction devices that operate in a lens shift manner and image shake correction devices that operate in a CCD shift manner. Image shake correction devices that operate in the lens shift manner correct image shake by driving a part of a lens installed in a lens housing according to hand vibration. Since a lens driven in the lens shift manner is lightweight, the lens may be constituted by a weak actuator; however, it is difficult to design the lens. On the other hand, an image shake correction device that operates in the CCD shift manner corrects image shake by driving the CCD according to hand vibration. An image shake device that operates in the CCD shift manner may constitute only a photographing apparatus without the need of a lens. However, since the driven CCD is relatively heavy, a strong actuator is needed. Thus, it is difficult to miniaturize the photographing apparatus, and power consumption of the actuator is large.
In order to address the problem described above regarding the image shake correction device that operates in the lens shift manner, U.S. Pat. No. 5,835,799 discloses an image shake correction device in which a magnet as a part of a driving portion for moving a lens for image shake correction in two directions that are perpendicular to an optical axis of the lens is installed as one body. The magnet is installed at a moving portion that moves in a correction direction in the state where the lens for image shake correction is supported. An electronic driving force is generated in the magnet due to a coil installed at a prop supporting the moving portion so that the position of the lens can be corrected. Such an image shake correction device may be implemented in a simple structure.
In addition, U.S. Pat. No. 6,064,827 discloses an image shake correction device in which a moving portion moving a support and a support for a lens are formed as one body and the support for the lens is elastically pressurized on a prop in the state where a plurality of balls are inserted between the support and the prop. In the image shake correction device disclosed in U.S. Pat. No. 6,064,827, the balls must be rolled within a range where the lens is corrected, which results in a reduction in sliding resistance that has an adverse affect on a correction driving force.
Japanese Patent Laid-open Application No. hei 4-180040 discloses an image shake correction device in which a support supporting a lens and a moving portion moving the support are separately constituted. In the image shake correction device disclosed in Japanese Patent Laid-open Application No. hei 4-180040, the support and the moving portion are separately constituted so that the lens can be easily moved in each moving direction.
However, in the image shake correction devices disclosed in U.S. Pat. No. 5,835,799 and U.S. Pat. No. 6,064,827, the support supporting the lens and the moving portion moving the support are constituted as one body. Thus, even when the support is moved in only one direction, the moving portion moves. In other words, the weight of the moving portion that does not need to move is included in a driven weight. Thus, a correction driving performance may be easily degraded. In addition, a moving range of the moving portion that does not need to move is required. Thus, the image shake correction device may be relatively large in size.
In addition, in the image shake correction device disclosed in U.S. Pat. No. 6,064,827, when the moving portion moves with respect to the prop, the moving portion is not securely guided and controlled in two directions. Thus, even when the support is moved in only one direction, crosstalk due to slight movement of the support in other directions occurs, and a correction performance may be degraded.
In addition, in the image shake correction device disclosed in Japanese Patent Laid-open Application No. hei 4-180040, backlash occurs between the support for the lens and the moving portion in a correction direction and in the direction of the optical axis of the lens, and a correction performance is degraded. In addition, since the moving portion is installed in an external mould of the support supporting the lens, the image shake correction device is relatively large in size.